Currently, supporting a print mechanism of a printing device that has multiple horizontal print lines being generated by the printing device entails buffering all of the data for all colors that are in the image to be printed under an image forming area of the print mechanism. Generally, the print mechanism comprises one or more print heads.
Referring to FIG. 1, image data 100 to be printed is schematically illustrated as multiple lines of print data. The darker gray regions 102 represent image data to be printed, while the image forming area 104 represents image data that is under some portion of an image forming area of the print mechanism. The print mechanism may be located in a color laser printer, which includes moving mirrors, modulated lasers, and toner developers. The print mechanism may also be located in an ink printer, which includes one or more ink heads, a thermal printer, which includes thermal heating elements, or some other image forming mechanism.
In the example represented by FIG. 1, each color is being printed on a single line and each of these color lines is six lines away from another color line being printed, i.e., five lines of image between each color are not being actively printed, and some may have already been printed by some of the other colors. With the example of FIG. 1, there are four color lines being printed, specifically, cyan 106, magenta 108, yellow 110 and black 112. Each print line, cyan 106, magenta 108, yellow 110 and black 112, schematically represents a laser beam within the print mechanism that prints the respective line of print data for the respective color.
There may be multiple lines of a single color being written to the image data, for example, one working on even lines and one working only on odd lines. The multiple lines of the same color may have a different spacing compared to the spacing of the different colors. For example, if each color is printed as two lines at a time (one even and one odd) and the even lines are represented in FIG. 1, the odd lines for each color may be located directly below each of the same color's even lines. The odd line image forming lines may also be located farther away.
Generally, with most printing devices, the print mechanism moves along the print medium in a downward fashion. Thus, the print mechanism begins printing based upon the bottom portion of the image forming area 104, i.e., in the example of FIG. 1, the black print line 112 of print data. Once the black print line 112 of print data has been deposited on the print medium as a black line of color, as well as the yellow line 110, magenta line 108 and cyan line 106, the print mechanism will move further down along the print medium and another line of print data may be utilized to determine another line of color to be deposited on the print medium one line below lines 106, 108, 110 and 112 (specifically, lines 107, 109, 111 and 113). As the yellow print line 110 moves downward, it will print five more lines of data before it reaches line 112. Likewise, as the magenta print line 108 moves downward, it will print eleven more lines of data before it reaches line 112 and as the cyan print line 108 moves downward, it will print seventeen more lines before it reaches line 112. Thus, each line actually represents four lines of print data, one line of print data for cyan, magenta, yellow and black.
As previously noted, with the example of FIG. 1, there are four lines of colors being printed, specifically, cyan 106, magenta 108, yellow 110 and black 112. These are generally referred to in the art as C, M, Y and K, respectively. Thus, in the example of FIG. 1, there are currently 19 lines (within image forming area 104) of C, M, Y and K data buffered in some type of memory. Accordingly, in the example of FIG. 1, there are 76 lines of stored data (19 lines for each of the four colors C, M, Y and K within image forming area 104). For a dual beam system (two laser beams per color, with one laser working on even lines and one laser working on odd lines simultaneously), both laser beams desire data simultaneously. Thus, two lines of data are needed for each color and therefore, image forming area 104 needs to include an additional line of data, for example, line 113. Therefore, if the even and odd lines of data are adjacent to one another, there would be 80 lines of stored data (20 lines for each of the four colors C, M, Y and K within image forming area 104).
Such buffering of data requires a large amount of memory. Thus, if one may significantly lower the amount of data stored that is not being immediately used, less memory may be required in the printing device and thus, a cost savings may be realized.